Process and apparatus for the vulcanization of rubber goods and the treatment of other goods requiring heat and pressure



v 2,081,670 ER GOODS AND PRESSURE A. JOHNSTON THE PROCESS AND APPARATUS FOR VULCANIZATION OF RUBB THE TREATMENT OF OTHER GOODS REQUIRING HEAT AND Filed July 22, 1935 Patented May 25 1937 UNETD PATENT FFICE Alexander Johnston, Edinburgh, Scotland, as-

signor to The North British Rubber Company Limited, Edinburgh, Scotland Application July 22, 1935, Serial No. 32,624 In Great Britain December 22, 1933 7 Claims.

This invention relates to the vulcanization of rubber goods or heat treatment of other goods, where heat and pressure are required.

The object of the invention hereinafter described is to obtain the requisite supply of heat by improved means which will also allow the heat to be controlled so that it may be kept uniform during the vulcanizing period.

The invention consists in obtaining the neces- 10 sary heat by the compression of air or gas above a predetermined working pressure in a closed circuit, and allowing the compressed and heated air or gas to expand down to the working pressure of the circuit.

The invention also consists in using a compressor to obtain suitable temperature and/or pressure conditions within a chamber containing the goods to be treated, by drawing air from the atmosphere, after which the compressor is adjusted to draw air from, and force air into, the

chamber in a working circuit, there being arranged in such circuit a regulating valve, preferably one which provides for an automatic control.

Reference will now be made to the accompanying drawing which illustrates diagrammatically by way of example, a vulcanizing installation constructed according tothe invention, and in which:

Figure l is a plan View partly in section of a vulcanizing installation according to the invention,

Figure 2 is an end elevation with the vulcanizing chamber in section.

In carrying the invention into efiect according to one embodiment, the vulcanizer casing or drum a. is mounted horizontally on supports 1) and fitted at one end with a door 0. A series of movable racks or wagons d carrying the goods to be treated are mounted on wheels e adapted to run on rails J fixed in the lower part of the drum on supports 9 whereby the goods may conveniently be run into, or withdrawn from, the vulcanizer.

Along one side the vulcanizer casing a is fitted with a number of inlet branches h leading from a manifold j which in turn is connected at k to the delivery of an air compressor Z. A similar series of outlet branches in are arranged along the 50 other side of the casing a leading to a manifold 11.,

which is in turn connected by pipe 0 to the suction side of the compressor. The same side of the compressor is fitted with a pipe p leading from atmosphere and a suitable three-way valve 55 (not shown) is fitted at q, whereby air may at first be drawn in through pipe p from atmosphere and passed into the vulcanizer through the inlets h, and when sufficient pressure has been obtained, the valve at q is adjusted to close the pipe 33 and open the return pipe 0 leading from the vulcanizer and pump it back again into the vulcanizer in a closed circuit. Before returning to the vulcanizer the air is passed through an automatic and adjustable compression valve at r, of any usual type. 10

The compressor Z may be of any suitable type and be driven for example by an electric motor 3. Preferably the compressor is of a two-stage type, high and low pressure respectively; both stages are used during suction from atmosphere, but 15 during suction from vulcanizer the high pressure cylinder is used. The details of the compressor have not been illustrated since such devices are well known, and as will be explained any suitable means may be used to cool the compressor. 20 Moreover, suitable heating means may be provided in or on the vulcanizer a, to act as auxiliary heating means when required. It is preferred to use electrical heating, and coils for this purpose are indicated at t.

The method of working is as follows:

After a certain amount of electrical heating of the vulcanizer to Warm up the shell and other parts, the compressor is started so as to draw air with corresponding adjustment of the valve q 30 from the atmosphere through the pipe p. This is continued until the air thus introduced into the vulcanizer attains a predetermined pressure, such as for example a temperature of 212 F. and 40 lbs. pressure per square inch. 5

The valve q is then adjusted so as to close pipe p and open pipe 0: by which the compressor will draw air from the vulcanizer, compress it through the automatically controlled valve 2" (adjusted to give the pressure desired) and discharge it back 40 into the vulcanizer, in a closed circuit.

By continued operation upon the closed circuit, the pressure on delivery from air compressor may be raised to 100 lbs. per square inch with an approximate temperature of 360 F., the air enter a ing the compressor at a temperature approximating to 250 F.

In connection with the electrically heated elements in the vulcanizer these may be regulated and cut out by thermostatic control. The regulation of air temperature in the compressor is carried out by cooling water and this is increased or decreased as required. Moreover, further reg ulation can be effected by thermostatic control 55 operation from the vulcanizer acting in conjunction with the valve 1.

Whilst it may be stated that according to the example of pressures above stated a final air temperature on leaving the compressor is attained at 400 F. the apparatus may however, be designed to work with other ranges of pressures.

The above described apparatus has been found in practice to give a pressure in the vulcanizer which is extremely steady.

By the above described installation a very accurate degree of temperature may be obtained and maintained at the exact uniform degree required and this may extend over any period desired. The pressure and therefore the temperature in the working circuit may be increased at any time by closing the pipe from the vulcanizer and opening the atmospheric pipe together with regulation of the valve 1, and after the desired pressure is recorded in the vulcanizer and circuit, the atmospheric valve q would be closed and the vulcanizer pipe opened and the throttle valve r adjusted as required.

In conclusion, more than one vulcanizing chamber may be controlled at a time, and it is to be understood that the invention is not confined to the vulcanizing of rubber goods, it may be applied to the treatment of other articles requiring heat and pressure.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Improved method for the vulcanization of rubber goods or the treatment of other goods requiring heat and pressure, which consists in obtaining the necessary heat by the compression of air or gas above a predetermined working pressure in a closed circuit and allowing the compressed and heated air or gas to expand down 40 to the working pressure of the circuit.

2.'A method for the vulcanization of rubber goods or the treatment of other goods requiring heat and pressure which consists in placing the goods in a closed container the gaseous atmos- 45 phere of which is maintained at a pressure higher than atmospheric pressure, withdrawing a portion of such gaseous atmosphere and compressing it to a higher pressure whereby it is heated, and delivering the compressed and heated atmosphere 50 to the container through a throttle valve.

3. A method for the vulcanization of rubber goods or the treatment of other goods requiring heat and pressure which consists in placing the goods in a closed container, compressing air or gas from a source external to the container and raising the pressure and temperature of the interior of the container by forcing said air or gas under pressure into the container and subsequently shutting oif said external source and drawing a portion of the compressed air or gas from the container, compressing it to a higher pressure and delivering back the compressed and heated air or gas to the container through a throttle valve.

4. A method as claimed in claim 3 which comprises automatically controlling the admission of the air or gas to the container in accordance with the temperature of the container.

5. Apparatus for the vulcanization of rubber goods or the treatment of other goods requiring heat and pressure, comprising a chamber containing the goods to be treated, a compressor, a piped connection from the compressor, an adjustable valve in such piped connection, a duct leading from the atmosphere to the compressor, and a piped connection from the chamber to the compressor, and valve means whereby the connection with atmosphere may be closed, and a closed circuit obtained between the chamber and compressor, or such circuit may be interrupted so that the compressor may pass atmospheric air directly into the chamber.

6. The method as claimed in claim 3 in which additional heat is directly applied to the air or gas in the container.

7. A method for the vulcanization of rubber goods or the treatment of other goods requiring heat and pressure which comprises compressing air from an outside source, thereby raising its temperature and pressure and forcing it into the container, allowing the air to expand in the container but preventing its expansion to such an extent as to transform all the heat of compression imparted to it, thereby raising the pressure and temperature within said container, shutting off the communication with the outside source when the temperature in the container reaches the desired point, alternately thus compressing and expanding the air in a closed circuit comprising the compressor and container, the compression taking place in the compressor and the expansion taking place in the container.

ALEXANDER JOHNSTON. 

